From a spring plate standpoint there is only so much toe adjustment built into the slots from factory. The further a suspension deviates from 3 o'clock the more toe-in becomes an issue. Stock spring plates do not have enough adjustment built-in to deal with the angles of excessive indexing. Quality drop plates are designed with proper slotting to deal with these toe issues.

When you severely lower a Beetle, the toe changes much more on a swing axle car than IRS. With stock swing axle spring plates, you do run out of slot, but not with IRS. Since the toe changes less with IRS, the stock slot length is capable of being set to zero at any ride height. Almost as if VW expected us to lower our cars!
When I had my car really low, I had to use Type 3 front snubbers on my rear TAs. (T3 snubbers are a lot shorter) This allowed the suspension to compress further than stock. I had no trouble setting the toe properly.

sidemarkers wrote:

A spring plate in the factory height location is a fraction of an inch from the bottom ledge. This is not just "air space" it's designed to keep the suspension in control by limiting body roll around corners. Lowering via indexing increases this distance which also greatly increases the body roll
and subsequent toe fluxuations between wheels when cornering.

We all know a Beetle in factory form is not going to win any road course races, it was designed to be a cheap car with a ride as good as it can be. IOW, handling wasn't much of a concern.
If you were to set up a Beetle for racing, lowering would likely be in order. Any racer knows that whenever a car hits a suspension stop, you have a good chance of losing control.
Let's say you take a hard right hander in a race prepped VW. The left TA will compress up while the right will drop. If you had drop plates, the right side will likely hit the bottom stop. When this happens, the wheel will lift off the ground. While that tire is in the air, it provides zero cornering traction. With a stock spring plate that is allowed to drop further, it remains in contact with the ground, providing traction.
Drop plates are not an advantage on the track.

sidemarkers wrote:

The drop plates I installed are .150 smaller in diameter so replacing the bushings was necessary from a design standpoint. The older ones did have some wear and it's likely the larger surface area of the new bushings provide more dampening ability.

Drop plates might not be a silver bullet, but the differences are noticeable while driving.

I'd say the difference you noticed was due to the poly bushings providing better control of the outer end of the torsion bar. I noticed similar effects when I put them in my car._________________